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Evidence for Environmental Changes in the Submillimeter Dust Opacity
Martin P. G., Roy A., Bontemps S., Miville-Deschênes M.-A., Ade P. A. R. et al
Astrophysical Journal 751 (2012) 28 - http://hal.archives-ouvertes.fr/hal-00664696
Planète et Univers/Astrophysique/Astrophysique stellaire et solaire
Physique/Astrophysique/Astrophysique stellaire et solaire
Evidence for Environmental Changes in the Submillimeter Dust Opacity
Peter G. Martin, Arabindo Roy, S. Bontemps1, 2, 3, 4, Marc-Antoine Miville-Deschênes, Peter A. R. Ade, James J. Bock, Edward L. Chapin, Mark J. Devlin, Simon R. Dicker, Matthew Griffin, Joshua O. Gundersen, Mark Halpern, Peter C. Hargrave, David H. Hughes, Jeff Klein, Gaelen Marsden, Philip Mauskopf, Calvin B. Netterfield, Luca Olmi, G. Patanchon5, Marie Rex, Douglas Scott, Christopher Semisch, Matthew D. P. Truch, Carole Tucker, Gregory S. Tucker, Marco P. Viero, Donald V. Wiebe
1 :  OASU - Observatoire aquitain des sciences de l'univers
http://www.oasu.u-bordeaux1.fr/
CNRS : UMS2567 – INSU – Université Sciences et Technologies - Bordeaux I
0ASU - Site de Floirac 2 rue de l'Observatoire - BP 89 33270 FLOIRAC
France
2 :  Université Sciences et Technologies - Bordeaux 1
http://www.u-bordeaux1.fr
Université Sciences et Technologies - Bordeaux I
351 cours de la Libération - 33405 Talence cedex
France
3 :  LAB - Laboratoire d'Astrophysique de Bordeaux
http://www.obs.u-bordeaux1.fr
CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
2 rue de l'Observatoire B.P. 89 33270 FLOIRAC
France
4 :  L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
http://www.obs.u-bordeaux1.fr
CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
BP89 33270 Floirac
France
5 :  APC - UMR 7164 - AstroParticule et Cosmologie
http://www.apc.univ-paris7.fr/
CNRS : UMR7164 – IN2P3 – Observatoire de Paris – Université Paris VII - Paris Diderot – CEA : DSM/IRFU
APC - UMR 7164, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, case postale 7020, F-75205 Paris Cedex 13
France
FORMATION STELLAIRE 2012
APC - Cosmologie et Gravitation
The submillimeter opacity of dust in the diffuse Galactic interstellar medium (ISM) has been quantified using a pixel-by-pixel correlation of images of continuum emission with a proxy for column density. We used three BLAST bands at 250, 350, and 500 \mu m and one IRAS at 100 \mu m. The proxy is the near-infrared color excess, E(J-Ks), obtained from 2MASS. Based on observations of stars, we show how well this color excess is correlated with the total hydrogen column density for regions of moderate extinction. The ratio of emission to column density, the emissivity, is then known from the correlations, as a function of frequency. The spectral distribution of this emissivity can be fit by a modified blackbody, whence the characteristic dust temperature T and the desired opacity \sigma_e(1200) at 1200 GHz can be obtained. We have analyzed 14 regions near the Galactic plane toward the Vela molecular cloud, mostly selected to avoid regions of high column density (N_H > 10^{22} cm^-2) and small enough to ensure a uniform T. We find \sigma_e(1200) is typically 2 to 4 x 10^{-25} cm^2/H and thus about 2 to 4 times larger than the average value in the local high Galactic latitude diffuse atomic ISM. This is strong evidence for grain evolution. There is a range in total power per H nucleon absorbed (re-radiated) by the dust, reflecting changes in the interstellar radiation field and/or the dust absorption opacity. These changes affect the equilibrium T, which is typically 15 K, colder than at high latitudes. Our analysis extends, to higher opacity and lower T, the trend of increasing opacity with decreasing T that was found at high latitudes. The recognition of changes in the emission opacity raises a cautionary flag because all column densities deduced from dust emission maps, and the masses of compact structures within them, depend inversely on the value adopted.
Anglais
2012

Astrophysical Journal (Astrophys. J.)
Publisher American Astronomical Society
ISSN 0004-637X 
internationale
Articles dans des revues avec comité de lecture
05/2012
751
28

Astrophysics - Galaxy Astrophysics
14 pages, 8 figures soumis APJ 2012
FORMATION STELLAIRE 2012

Lien vers le texte intégral : 
http://fr.arXiv.org/abs/1112.5433